YZ400 smoking when it first starts until it warm?

yamahauler44

i am noticing that when i start my 1999 YZ400F it behaves fine and is easy to start has plenty of compression, has plenty of power, ect. but if i rev the motor before its warm it smokes a little, not a huge plume or anything just a little, if i dont rev the motor untill it warms up there is no noticable smoke. have any of you had this before? is it normal or not? give me the run down. thanks in advance.

YZ400FPower

I dont know. It dosent sound bad but my 400 dosent do it. If it gets worse you should check your seals. Oil can get caught inside the exhaust. Take that off and if there is oil id go into the motor. Thats what I would do. Please correct me if im wrong fellas!

RogerDedrick

My 426 smoked on start when it had not been run for a few days to a week. I replaced the oil seals and the piston. The rings were fine but the valve stems had a build up of sludge from the leaking oil.